1. Field of the Invention
The invention relates to a charged particle multi-beamlet lithography system for transferring a pattern onto the surface of a target using a plurality of beamlets. The invention further relates to a modulation device for use in a charged particle multi-beamlet lithography system, and to a method of manufacturing such a modulation device.
2. Description of the Related Art
Charged particle multi-beamlet lithography systems are known, for example from U.S. Pat. No. 6,958,804. The system described in this patent preferably uses a plurality of electron beamlets to transfer a pattern to the target surface. The electron beamlets generated by a radiation source are modulated in a modulation device by electrostatic deflection in accordance with pattern data. The modulated beamlets are then transferred to the target surface. To enable high speed transfer of the pattern to the target surface, the pattern data for controlling the electrostatic deflection are transferred at least partly using optical transmission using modulated light beams.
Another charged particle multi-beamlet lithography system is known from Jpn. J. Appl. Phys. Vol. 32 (1993), Part 1, no 12B, pp. 6012-6017. The modulation device of this system comprises an array arranged for the individual deflection of 1024 beamlets. For this purpose, the modulation device comprises a substrate with 1024 apertures, each in the form of a square of 25 μm×25 μm size. The pitch of the apertures is at least 55 μm. Electrodes are provided at the edge of the apertures for generating an electric field across the apertures for deflecting a passing charged particle beamlet. Pattern data are transferred to the electrodes via wires.
In European patent application 1 453 076 it is recognized that the use of a plurality of electron beams comprising a plurality of individually controlled blanking electrodes in the form of an array as discussed in the abovementioned article creates difficulties with respect to the formation of a suitable wiring structure. To enable the use of more interconnects via wiring within a limited space European patent application 1 453 076 proposes to form a wiring substrate having a multilayered wiring structure and an electrode substrate having a plurality of through holes and an electrode pair on opposite side walls of each through hole to control the locus of a charged particle beam passing therethrough. The wiring substrate and the electrode substrate are then bonded such that connection wiring pads of the wiring substrate are connected to the electrode pairs of the electrode substrates. Construction of separate substrates and subsequent bonding is time-consuming and costly. Furthermore, alignment of the two substrates with respect to each other is cumbersome.